Field of the Invention
Performance characteristics required of many gaskets includes both compression failure resistance and sealing ability. Gaskets frequently must operate under pressures in the range of from about 3,000 to about 30,000 PSI (pounds per square inch). At the same time the gasketing is also required to provide a seal against fluids.
In some instances, in order to provide a good seal, gasketing is coated to get sealing ability. Fibrous gaskets or soft porous materials are types of gasketing which is given coatings since this gasketing is very porous and has problems in giving an adequate seal for use. Unfortunately, the coating used to give sealing ability penetrates the gasket, and reduces the ability of the gasket to withstand pressure. It would be beneficial to develop a gasket which delivers good sealing ability which, at the same time, is compression-failure resistant, especially if the gasket could operate at flange pressures in the range of from about 20 to about 30,000 PSI.
Gasketing which is presently known in the art includes gaskets described by U.S. Pat. No. 3,661,401 which requires that the gasketing be given a coating which covers the walls of the apertures in addition to the gasketing faces. Such gasketing, however, being completely coated, will perform poorly at such high pressures. This severely limits the field of use of the gaskets.
The present invention beneficially provides gaskets which have an adequate sealing ability and are compression-failure resistant. Gaskets which are capable of withstanding operating pressures of at least 3,000 PSI are provided. Furthermore, gaskets which operate well in the range of from about 20 to about 30,000 PSI are provided; the present gaskets remarkably being capable of sealing at both high and low flange pressures.